The US Senate was considering a bill to extend the closing deadlines for the home buyer tax credit until September 30, but the measure appears dead. The proposal was actually not to extend the tax credit itself, rather to allow buyers who entered into a purchase contract before April 30, 2010, to still obtain the credit as long as they closed on the purchase by September 30, 2010. The current deadline states that the transaction must close before June 30 in order to obtain the tax credit.
The logic behind the proposal was that many buyers are unable to meet the June 30 deadline because their lenders are overwhelmed with transactions or because the buyers are waiting for uncertain and lengthy review processes for short sales. The proposal was tacked on to a bill that included a number of tax and spending measures, but has been shelved after it failed a number of votes.
Anything is possible with the lawmakers in Washington DC, but for now the original deadline stays the same, so you must close your home purchase by June 30 to obtain the credit. It remains to be seen if the measure will be reintroduced in Congress.